The SMC Pentax-DA 50mm F1.8 lens is designed for the APS-C sensor format and performs like a small telephoto lens in that format (75mm eqv.).

Pentax promises a superb rendition of depth and a natural bokeh (out-of-focus) effect in part thanks to the rounded aperture blades.

It features a lightweight plastic construction with a plastic lens mount similar to that of the DA 35mm F2.4. The large maximum aperture of F1.8 produces a shallow depth of field which is ideal for portrait photography.

The front element is SP coated so as to repel dirt and grease and be easier to clean.

This lens is an affordable alternative to the DA* 55mm F1.4 lens. It will cost $249 and be available in late June / early July, 2012. It has a plastic bayonet.

This lens is very usable on full-frame K1. Sharp enough to feed the great 36mp sensor. Edges and corners are very good, too. Recessed front element - there is not much need for a hood. Very light and portable. The only con may be noise in focusing but most my lenses are screw drive anyway.

Compared with an old 50 M 1,7 this lens is pure crap. Soft, almost unusable at 1,8, cold colors which almost everyone hated it, no manual controls, cheap feel & all of this at a much higher price than competition. I wonder why they just dont take the old lenses & put some AF motors on them?

This is an amazing lens. Many pros, just a few cons, and at 150$CAN (110 $US equivalent at the time of purchase), there's no reason not to buy this lens, unless you already have a fast 50.

First off, sharpness. Even wide open, the lens is already very sharp in the center. It has a slight "dreamy" effect, which is due to the lack of contrast. A bit of contrast tuning in post-production makes the dreamy effect go away, with nice results. Stopping down the lens raises its contrast and its sharpness, with very sharp results across the frame from F2.2 and amazing sharpness from F2.8!

Lateral chromatic aberrations are on the high side wide open, and I've run into purple fringing at times (only on metallic or similar objects reflecting the sun's light, though). However, the CAs can be corrected easily in post-production. The longitudinal chromatic aberrations are also present wide open, but are lower than expected. All this is to be expected from a non-apochromatic lens, so there's no surprise, here.

Distortion is low and not of any concern unless you're into architecture photography. Vignetting is visible wide open, but it's also very well controlled.

The bokeh is very impressive wide open, and still good when stopped down. Excellent for portraits and to separate your subject from a busy background, which will turn to cream depending on the distance.

AF speed is great, but I found the AF very hesitant and quite inaccurate wide open. Obviously, shallow depth of field is not helping the camera to focus, but I wasn't expecting the lens to miss focus 90% of the time in good light when shooting wide open. The AF is also quite noisy, which, combined with the poor focus performance, can be a bit annoying. Thankfully, manual focus is a breeze, thanks to a perfectly damped focus ring.

The lack of a real lens hood is a bit of a bummer, as the lens is a bit sensitive to flare. The plastic mount is a disappointment, but at such a low price, I wasn't expecting a metal one. Still, the construction is rather impressive, with a tight assembly.

At such a low price, the only reasons why you wouldn't have this lens in your camera bag is either because you have no use for a fast prime with a 50mm focal length or because you already have a fast prime in the 35-70mm focal length.

This ultra-cheap, ultra-light, plastic lens is actually very well, tightly built.
The sharpness, center and edges, for reasons I don't know of, is better at full aperture than the A 50/1.7 and FA 50/1.7.
Quickshift is sorely missed. I would have like a hood also.

I bought my DA 50mm, as I was les than satisfied by the results I was getting with my 50mm A f1.7 on my K3. I already had the DA 35mm f2.4 and I am pretty pleased with that lens, but I do like the 50mm focal length an APSc cameras.
The DA 50 is definitely the best lens I own in terms of IQ on the K3. Pictures are consistently sharper with excellent contrast and colour rendition. I paid £90 for my copy so its also a damn good bargain!
My only criticism is that it does not function properly when used with my KA extension tubes. It only shoots at full aperture. There must be some fault in the communication between lens and camera. Funnily though me DA 35mm does work OK with the same tubes!
I've scored this lens as a 10 because of its overall IQ and great value for money. If it were more expensive I would be a little disappointed with the extension tube issue and could be picky about the plastic mount. I would still rate it as a 8.5/9.0 though.
If you don't have, one do yourself a favour get one!

Image quality is practically identical to Pentax A 50mm 1.7. I the image centre DA at f1.8 is as sharp as A at 1.7 but in the corners of the image DA is sharper.

Bokeh as well as bokeh rings looks similar but photos from A are slightly better.

When full open images are soft but acceptable, good news is that steeping it down to 2.0 helps to remove soapy blur and slightly increases sharpness. At 2.2 it starts to be really sharp.
Auto focus is not to accurate, you can easily focus not exactly on object of your interest which happened few times during the test.
Focusing is the biggest problem it might happen that image taken with 2.0 can be sharper then one taken at 2.8… In general lens is sharp and there is no big difference between it and A1.7 sadly performance is limited by focusing system which is very inaccurate. I cannot say is it fault of SAFOX X auto-focus system, lens or both but it fails to deliver as good images as optics of the DA are capable of...

I Love the old manual 50mm asahi pentax smc lenses from F/2 down to F/1.4 - this is as good as those but better :-) It is obviously an AF lens vs. MF lens, but sometimes having the MF control is nice. That being said, this lens almost always hits its focus target relatively quick.

Sharpness:8Aberrations:8Bokeh:9Autofocus:7Handling:6Value:10New or Used:New

This is a great little lens for the price. On the K-1 you get a perfectly usable "normal lens". Vignetting wide open is there but not heavy. It's very light and small. Of course it lacks the build & comfort of the Limiteds (focus override). Only downsides (no big ones though) are the rather loud focusing noise and the 52mm thread. No idea why Pentax built this diameter since there's space enough. I bought a simple 52-49 step-down ring, which causes no problems whatsoever even if I use my 49mm filters on top.

Thought I could never bring myself around to buying a lens with a plastic mount, but am extremely glad I did, because IQ-wise this nifty fifty is an absolute no-brainer. Found myself pixel-peeping, because I couldn't believe what I was getting for the money.

Granted, contrast at F1.8 isn't all that hot but still what I'd call usable, particularly for portraiture and with your model in the centre of the frame. Stop down to F2.5, and you get decent sharpness. Anything between F2.8 and F11 (or, heck, F16) gets tack-sharp, if you've achieved focus. Invites shallow-DOF shooting, given the nicely-creamy, yet not boringly-muddy bokeh.

Seriously, get one today and prepare to be amazed. If it should break (which is unlikely to happen unless you abuse it), get another.

Here are some doggy portraits and some shots from Haarlem and Amsterdam, all done with the DA50:

The DA 50mm f1.8 holds a special place with me: it is the first prime I bought when I bought into the Pentax DSLR scene. I bought my gently-used copy from another PF member here through the Marketplace.

I call it 'Sunday Morning' since it's so easy...to shoot with. First and foremost - why is this NOT a DA L lens? Plastic mount, relatively inexpensive to manufacture, minimal markings (no distance scale, no aperture ring), and nearly without a focus ring.

AKA the 'plastique fantastique' - this is an amazing lens for the money. I bought mine used from another shooter here on PF for less than $100 and have been amazed pretty much every time I mount it. One of the criticisms I've read about the DA50 is that it has little character, that is produces shots that can be clinical in quality. I prefer to look upon it as a positive, and revel in its clarity, detail, and honest color rendition. The lens is easy to handle and practically makes my K-3 (and K-50 before that) a point-and-shoot camera.

I used this lens in May for the Single In Challenge and I enjoyed the month (especially after the 135 desolation of April) with the DA50 - it never let me down, it was able to produce quality images pretty much every day, and seemed to have few limitations. On the downside, it's lack of aperture ring and poor focus ring really can try your patience if you're wanting to work more manually. Its minimum-focus-distance of about a foot and a half can be trying at times, but take a step back and let it fly.